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Hi, I found my bug, but I want to understand why the compiler did that! I use a fonction to clear bits: CLRBIT(BYTE, MASK); The following C code: CLRBIT(aBMCURegisters[REGADDRESS], I2C_SELECT_BIT | DDC_BYPASSN_BIT); Compile this ASM code: ANL aBMCURegisters+01H,#07FH Which is wrong because, the definition of bits are: #define DDC_BYPASSN_BIT bmBIT2 #define I2C_SELECT_BIT bmBIT7 It's like the compiler only check the first bit of the second argument! To compile a right code, I need to put the second argument between (), like this: CLRBIT(aBMCURegisters[REGADDRESS], (I2C_SELECT_BIT | DDC_BYPASSN_BIT)); Compile this ASM code: ANL aBMCURegisters+01H,#07BH Please note that the C code use only one line... (no return between args). Do you know why? Thanks, Denis.
That's still not careful enough. The two most important rules for writing function-like macros are: *) put a pair of parentheses around every use of any of the arguments. *) put another pair of parentheses around the whole macro body This a basic FAQ-level C knowledge. You should be beyond that if you're going to write embedded C.
I agree with you, except that I wrote some code in the past with some micro devices and I never used macros... It's not a necessary knowledge when the compiler support inline function. I beleive that C51 should also support it! Do you?
when the compiler support inline function. I beleive that C51 should also support it! it does. That it does it in a crummy way (no debug of C source etc) is another story. Erik
"I beleive that C51 should also support it!" It's an ANSI compiler. Where does ANSI say anything about inline functions?